I had the same questions when I first started up my ninja. Because my radiator cap was bad for all that time and after I replaced it, I didnt know how hot the bike could get. I was told between 180-260 (i dont remember exactly so correct me if im wrong) is okay. Aabout 220, my fan came on and it stayed at 220. I asked a bike friend of mine and he says these temps are normal, espcially in our hot climates grafixx. :dthumb: